While teaching summer school may require similar skills as reading intervention during the year, rarely are summer school instructors reading specialists. To support these instructors providing high quality instruction, this research study examined the impact of the 95 Phonics Booster Bundle: Summer School Edition (SSE). The SSE is a set of 25 fully-scripted lessons with HTML presentation files designed to quickly bolster phonics skills that had been covered in the previous school year. 95 Percent Group hired LXD Research to conduct an independent evaluation of the SSE. LXD Research designed a quasi-experimental study to determine the ability of SSE to support literacy skill development over the summer months. The Acadience Reading assessment was administered to assess student outcomes (testing occurred in the Spring and Fall). Study 1 used one SSE lesson a day over six weeks, and Study 2 intensively used two SSE lessons a day over one month. LXD Research collected data from 958 students in grades 1-3 to determine the efficacy of the 95 Phonics Booster Bundle SSE product. 479 students were assigned to use SSE and 479 were included as statistically similar comparison students who did not use SSE. The study was conducted in Summer 2021, and spanned two school districts, one in California (63% Hispanic) and one in Arizona (46% Hispanic). Rising first graders who completed one SSE lesson a day across six weeks outperformed similar students who did not attend summer school, according to the Acadience Reading assessment, where SSE students showed an 8-point gain compared to a 6-point slide. For rising third graders who were Well Below Benchmark, students who completed two SSE lessons a day for one month outperformed non-SSE students on Acadience Reading, showing a 16-point gain compared to a 4-point slide. Results for other groups were comparable to the comparison students. The significance of the findings and the rigorous study design provide support for 95 Phonics Booster Bundle SSE as a program that meets the criteria for ESSA Level 2. The findings indicate that the 95 Phonics Booster Bundle SSE is a powerful tool for schools to use to support early literacy and reading development. [This report was produced by LXD Research and 95 Percent Group.]